lack of recoil-operated semi rifles?... why?

[Nom de Forum]

A related question I am hoping to have answered is why the HK series of arms that are delayed-blowback still have some type of op rod on top?

I'm curious in the main points of the thread too since I love firearm design and learning more about it, and I may look into some of those publications for fun when I have some time.

That is not an op rod. It is the Bolt Head Carrier with Recoil Spring Tube.

 

[barnbwt]

And that, sawdeanz, is the first step towards realizing what a wasteful and inelegant device the ostensibly "perfect" G3/CETME action is. Step two is learning about the need for a self-tensioned bolt head (and the leveraged-cocking handle it requires to open the action), step three the absolute dog's breakfast of a trigger group design. 3.1 would be the pivoting blade ejector, specifically. Fourth would be a selector lever that Jerry Miculek probably has a hard time thumbing (moreso on the CETME). To be honest, the gun was just about as much a piece of work as a design as the M16 ever was, it's just that its issues were more quickly found/solved before it went into action. The one elegant solution in the gun is the way H&K decided to do a forward assist; they put thumb serrations/scallops on the bolt body (can you honestly say the kludge on the side of the AR15 is a better solution for easing the bolt home?)

Oh, it's quite efficient and easy to build...if you have a nation-scale waffenfabrik facility already in place

TCB

PS: Fun fact; a guy going by holescreek converted a G3 to gas operation. IIRC, he replaced the rollers with wedges (so they could not roll and cam back the bolt body) and ran a long-stroke gas piston down the cocking tube housing to a gas block hidden in the front sight triple tree. Worked great, and completely eliminated the need for chamber flutes . I believe it was in 243, or some other caliber it'd be impossible to get a fluted H&K barrel for

 

[Nom de Forum]

And that, sawdeanz, is the first step towards realizing what a wasteful and inelegant device the ostensibly "perfect" G3/CETME action is. Step two is learning about the need for a self-tensioned bolt head (and the leveraged-cocking handle it requires to open the action), step three the absolute dog's breakfast of a trigger group design. 3.1 would be the pivoting blade ejector, specifically. Fourth would be a selector lever that Jerry Miculek probably has a hard time thumbing (moreso on the CETME). To be honest, the gun was just about as much a piece of work as a design as the M16 ever was, it's just that its issues were more quickly found/solved before it went into action. The one elegant solution in the gun is the way H&K decided to do a forward assist; they put thumb serrations/scallops on the bolt body (can you honestly say the kludge on the side of the AR15 is a better solution for easing the bolt home?)

Oh, it's quite efficient and easy to build...if you have a nation-scale waffenfabrik facility already in place

And that, sawdeanz, is how you end up with "something unstoppable but with no other redeeming qualities" to quote some guy here on THR always going on about such things with such entertainingly blinding brilliance that he could slip in some entertainingly baffling BS and most people would never catch it. BTW the HK91 was the first military style rifle I ever purchased. It is exactly as barnbwt describes.

PS: Fun fact; a guy going by holescreek converted a G3 to gas operation. IIRC, he replaced the rollers with wedges (so they could not roll and cam back the bolt body) and ran a long-stroke gas piston down the cocking tube housing to a gas block hidden in the front sight triple tree. Worked great, and completely eliminated the need for chamber flutes . I believe it was in 243, or some other caliber it'd be impossible to get a fluted H&K barrel for

Didn't I see that one time in a Rube Goldberg cartoon?

 

[Willie Sutton]

"for more modern ones there's Highpoint carbines, Kel-tec sub 2000, and the Beretta carbine"


I note that these are simple blowback designs, not recoil operated designs.

Not a rifle, but the classic Browning shotgun (and Remington Model 11 shotgun) are both long recoil designs as well. Remongton seems to have been the only maonstream maker interested in both rifles and shotguns using this engineering solution.


Willie

.

 

[Nom de Forum]

Hey Willie does that Mig you jockey around still have the 37mm installed?

 

[sawdeanz]

And that, sawdeanz, is the first step towards realizing what a wasteful and inelegant device the ostensibly "perfect" G3/CETME action is. Step two is learning about the need for a self-tensioned bolt head (and the leveraged-cocking handle it requires to open the action), step three the absolute dog's breakfast of a trigger group design. 3.1 would be the pivoting blade ejector, specifically. Fourth would be a selector lever that Jerry Miculek probably has a hard time thumbing (moreso on the CETME). To be honest, the gun was just about as much a piece of work as a design as the M16 ever was, it's just that its issues were more quickly found/solved before it went into action. The one elegant solution in the gun is the way H&K decided to do a forward assist; they put thumb serrations/scallops on the bolt body (can you honestly say the kludge on the side of the AR15 is a better solution for easing the bolt home?)

Oh, it's quite efficient and easy to build...if you have a nation-scale waffenfabrik facility already in place

TCB

PS: Fun fact; a guy going by holescreek converted a G3 to gas operation. IIRC, he replaced the rollers with wedges (so they could not roll and cam back the bolt body) and ran a long-stroke gas piston down the cocking tube housing to a gas block hidden in the front sight triple tree. Worked great, and completely eliminated the need for chamber flutes . I believe it was in 243, or some other caliber it'd be impossible to get a fluted H&K barrel for

Now I'm much more curious about this, didn't realize the design was so complex. You will understand now why I was confused in the first place. Though I always liked the look I could never understand how they could charge so much for a stamped rifle and why if it was so great it needed a fluted chamber. Of course they say its a feature for better reliability but I always figured that was just some bologna they were using to cover up some design handicap. Thanks for confirming my suspicions.

On the other hand G36's seem pretty neat, would like to see those in the states someday.

 

[Nom de Forum]

Now I'm much more curious about this, didn't realize the design was so complex. You will understand now why I was confused in the first place. Though I always liked the look I could never understand how they could charge so much for a stamped rifle and why if it was so great it needed a fluted chamber. Of course they say its a feature for better reliability but I always figured that was just some bologna they were using to cover up some design handicap. Thanks for confirming my suspicions.

On the other hand G36's seem pretty neat, would like to see those in the states someday.

The fluted chamber is not really bologna to cover-up a handicap as it does not create or obscure a limitation on performance. Delay-blowback systems typically do not have mechanical primary extraction so flutes are used to inject gas around the cartridge to "float it" out of the chamber during extraction. This works very well and despite what some people think does not prevent handloaders from reloading the case. Delayed Blowback has been a great operating system for some weapons. An example would be barnbwt's labor of love the Stgw 57 rifle he built, the SIG 510 rifle, SIG 710 GPMG, H&K MP5 SMG, H&K 21 GPMG, and others. Roller Delayed Blowback is not a weakness of the H&K 91/93 rifles. Excessive weight and poor ergonomics are these rifle's primary weaknesses.

 

[barnbwt]

Of course they say its a feature for better reliability but I always figured that was just some bologna they were using to cover up some design handicap

The 'handicap' is the same as if you'd taken an AR15 and been forced to make it run 308 --with no scaling up of components! The rifle is, at its core, really undersized for the power it's handling, so little tricks like the sprung bolt are needed to effectively multiply the force of the recoil spring shutting the action, while also effectively multiplying the bolt weight through mechanical disadvantage at the rollers. Even despite all this leverage slowing things down, the gun still extracts so violently (and so quickly) it will rip cases apart extracting them if they are not 'floated' off the chamber walls on chamber flutes.

Lots of theories about the flutes; the most recent hilarious one I read said the flutes created more surface area for the case to grab onto and thereby increase friction. The flutes are there because the undersized blowback action shifts enough initially while the case is still under pressure and nailed to the chamber walls, that that small shift in bolt face would tear the case body near the head (same as with long headspacing, but not ordinarily as violent due to the initial delay still slowing the process down a lot). By fluting the chamber, the pressure more or less equalizes on the case body, so it isn't glued so forcefully to the walls under pressure. Apparently only the very rear of the case wall area is needed to expand fully to obtain a gas seal, which is why the flutes don't go all the way back (and why the action doesn't vent huge quantities of gas through the flutes).

Even despite all these efforts, enough blowby gets past the flutes, along with whatever residual pressure is left when the case begins moving out of the chamber, that the action gets really nasty, quick.

I like the Swiss approach to delayed blowback better than the German's, because there is no tensioned bolt head. Instead, the bolt tail is about 10X more massive and simply pushes forward against the rollers/bolt head under a strong recoil spring. That, to me, seems like a much more straightforward design solution, though heavier. The heaviness of the srping I do not mind, since it dampens recoil enormously, unlike the G3 which absolutely brutalizes its brass (and flutes have nothing to do with that) since the little bolt carrier is flying around so fast in there (the unique ejection of the STGW helps a lot, too). The STGW is a heavy pig at 14lbs, but it's also built like a true LMG rather than a storm rifle (despite its name in German); long, heavy barrel, giant, heavy stocks, and a bipod. The actual gun between the trunnions isn't notably heavy, especially since the barrel trunnion is so much lighter than the G3. This gun is also shooting a round about the size/power of 30-06, FWIW; a <10lb select fire short barrel variant would be comically impractical (but totally cool)

The cocking system is also way simpler; there's just a non-reciprocating handle on the correct side of the rifle p) that rides in a slot, and pulls on the tail of the bolt carrier when yanked on. No super-sensitive, pain-in-the-rear, you'd-better-hope-this-doesn't-break-when-you-need-it lever charging handle with it's weirdo two-part folding/sliding operation. I know full well that H&K's stuff works well once assembled, but getting there is an enormous challenge for anyone outside their factories. A friend completed a CETME while I did my build, and while both were troublesome (that's just sheet metal receivers, for you) his build was far, far more challenging than mine. So long as the bolt drops through the receiver tube, the STGW will very likely work (assuming the barrel is made properly and parts aren't worn down). The CETME requires careful positioning of the pressed-in barrel, cocking tube, and front trunnion --and then you still have to hope your parts aren't worn down when you check your bolt gap. Lord help you if you accidentally let the bolt snap down under that crazy spring when it's out of the gun; dig out the bench vise and cheater bar

TCB

 

[Nom de Forum]

The 'handicap' is the same as if you'd taken an AR15 and been forced to make it run 308 --with no scaling up of components! The rifle is, at its core, really undersized for the power it's handling, so little tricks like the sprung bolt are needed to effectively multiply the force of the recoil spring shutting the action, while also effectively multiplying the bolt weight through mechanical disadvantage at the rollers. Even despite all this leverage slowing things down, the gun still extracts so violently (and so quickly) it will rip cases apart extracting them if they are not 'floated' off the chamber walls on chamber flutes.

Lots of theories about the flutes; the most recent hilarious one I read said the flutes created more surface area for the case to grab onto and thereby increase friction. The flutes are there because the undersized blowback action shifts enough initially while the case is still under pressure and nailed to the chamber walls, that that small shift in bolt face would tear the case body near the head (same as with long headspacing, but not ordinarily as violent due to the initial delay still slowing the process down a lot). By fluting the chamber, the pressure more or less equalizes on the case body, so it isn't glued so forcefully to the walls under pressure. Apparently only the very rear of the case wall area is needed to expand fully to obtain a gas seal, which is why the flutes don't go all the way back (and why the action doesn't vent huge quantities of gas through the flutes).

Even despite all these efforts, enough blowby gets past the flutes, along with whatever residual pressure is left when the case begins moving out of the chamber, that the action gets really nasty, quick.

I like the Swiss approach to delayed blowback better than the German's, because there is no tensioned bolt head. Instead, the bolt tail is about 10X more massive and simply pushes forward against the rollers/bolt head under a strong recoil spring. That, to me, seems like a much more straightforward design solution, though heavier. The heaviness of the srping I do not mind, since it dampens recoil enormously, unlike the G3 which absolutely brutalizes its brass (and flutes have nothing to do with that) since the little bolt carrier is flying around so fast in there (the unique ejection of the STGW helps a lot, too). The STGW is a heavy pig at 14lbs, but it's also built like a true LMG rather than a storm rifle (despite its name in German); long, heavy barrel, giant, heavy stocks, and a bipod. The actual gun between the trunnions isn't notably heavy, especially since the barrel trunnion is so much lighter than the G3. This gun is also shooting a round about the size/power of 30-06, FWIW; a <10lb select fire short barrel variant would be comically impractical (but totally cool)

The cocking system is also way simpler; there's just a non-reciprocating handle on the correct side of the rifle p) that rides in a slot, and pulls on the tail of the bolt carrier when yanked on. No super-sensitive, pain-in-the-rear, you'd-better-hope-this-doesn't-break-when-you-need-it lever charging handle with it's weirdo two-part folding/sliding operation. I know full well that H&K's stuff works well once assembled, but getting there is an enormous challenge for anyone outside their factories. A friend completed a CETME while I did my build, and while both were troublesome (that's just sheet metal receivers, for you) his build was far, far more challenging than mine. So long as the bolt drops through the receiver tube, the STGW will very likely work (assuming the barrel is made properly and parts aren't worn down). The CETME requires careful positioning of the pressed-in barrel, cocking tube, and front trunnion --and then you still have to hope your parts aren't worn down when you check your bolt gap. Lord help you if you accidentally let the bolt snap down under that crazy spring when it's out of the gun; dig out the bench vise and cheater bar

TCB

By your own admission the Stgw 57 is a pig at 14lbs. That pig is not much of a burden for Swiss soldiers who intended to use almost static defense tactics against invaders attempting to negotiate mountain passes. The H&K 91 a.k.a. Bundswehr G3 rifle’s “little tricks” make it 40% lighter enabling it to be much better suited to defending the plains of Northern Germany. The flutes do an excellent job “floating” the cases off the chamber walls. I have never seen a H&K rip-off a case head. The ejection is forceful, cases are dented by the ejection port, but in some situations excess ejection power is a good thing. Sure the receiver gets gunky from firing but it is no more serious problem than it is for a MAS 49 or M16, both known for getting gunky and still operating. I think H&K did a good job making the rifle design shoot a more powerful cartridge than it was originally intended to shoot. I agree the Swiss SIG is more elegant in design but it is very expensive and heavy. Long barrels in HKs seem to work fine in the PSG sniper version of the G3. I don’t know about heavy bullet working in an HK other than some cast lead 169gr reloads I shot in mine that all went bang and ejected. I do think the H&K design could handle the power of 7.5 Swiss Ball because if you do some checking you will find in military loadings it is nearly identical in power to 7.62 Nato M80 Ball and .30-06 M1 and M2 Ball.

Lord help you if you accidentally let the bolt snap down under that crazy spring when it's out of the gun; dig out the bench vise and cheater bar.

Naw, you don't need to worry about that or use a bench vise and cheater bar. Insert the Bolt Head Carrier backwards into the receiver until it stops. Smack the Bolt Head Carrier Recoil Spring Tube with the palm of your hand. The Bolt rollers will pop back in when the bolt moves. Remove the backwards Bolt Head Carrier then reassemble the rifle. That is the easy way. The harder way is to use strong hands to just pull the bolt head to pop the rollers in. I used to do that when I was younger and stronger.

 

[barnbwt]

"I have never seen a H&K rip-off a case head."
Shoot one without flutes, sometime . They really are quite necessary for function; it's not a 'reliability enhancement' at all. The ripping/tearing is most commonly seen in Century hack-jobs that are marginal at best in bolt gap, but it's happened with stuck cases, too (or at the least the case rim is ripped out). Strong ejection is nice, but ridiculous ejection is ridiculous; some of those G3's are straight up hazardous to anyone nearby (I've seen cases stuck into boards, before )

"I think H&K did a good job making the rifle design shoot a more powerful cartridge than it was originally intended to shoot."
Abso-tively. I honestly would love to have been a fly on the wall at CETME Engineering when the decision to go to 308 was made. I suspect there was a stony silence, then engineers one after another wondering how the heck they were gonna pull this off

Totally agree on the STGW being heavy. I think the best solution would have been if H&K could have adopted SIG's trunnion design (with replaceable recesses and like 1/3rd the weight of the CETME part) but adapted it to work with their simpler sheet metal form. The SIG bolt really isn't all that much heavier; the trunnion weight savings probably make up for it, in fact. With a simpler bolt setup, the modified H&K could have a basic non-folding charging handle with the original layout of a spring over the barrel, or a buffer tube inside a fixed stock like the SIG behind the bolt with a sliding handle on either side for charging. The H&K trigger pack concept is excellent, but they chose the most Byzantine way to go about doing a trigger; an AR, AK, or even SIG/Beretta system would be simpler to service by about a mile. The trigger group housings are oddly tank-like, as well.

As far as the PSG-1 (don't get me started on how overrated that thing is ), I know it has a different cam angle on its delay features, which likely accounts for its operability with the different barrel, though I think it was mainly to slow down initial recoil to aid accuracy. Roller delay can be tuned to just about anything, but I worry if for a cartridge as variable as 308 can be (110gr-200gr) that you could push past the design limits. You can do that in a Garand as well, of course, but you likely won't blow the case out in so doing (just bend the op rod). Roller delays simply have bigger consequences when they don't work right.

"I do think the H&K design could handle the power of 7.5 Swiss Ball because if you do some checking you will find in military loadings it is nearly identical in power to 7.62 Nato M80 Ball and .30-06 M1 and M2 Ball."
It's got significantly lower bolt thrust than either, IIRC (lower pressure), but has nearly identical case volume to '06, so it can get up higher in bullet weights than 308. The military GP11 is right up there with the other 30cal cartridges of the day, though (so much work by so many nations to make poor facsimiles of GP11 ). In higher loadings with more powder, I'd worry about the extra momentum from powder gas being dumped into an H&K action; those rollers just look so tiny already, and the action was already close to margin. It'd probably work, it'd likely just wear things out faster. Ultimately, the extra powder needed to launch extra-heavy bullets from these roomy cartridges like x55 and '06 is why they were phased out; they simply aren't as 'recoil efficient' as a 308, for the types of jobs they'd be used for

TCB

PS -you didn't have to go and give away the secret to unlocking the H&K bolt head like that --newbies have to earn their stripes, you know . If you own a Steyr M95, you too will have a special hatred for bolt designs that snap down like that (no clever trick for unlocking the Steyr bolt; you gotta just grab those sharp surfaces and rip the bolt open)

 

[briansmithwins]

In theory it would seem that the HK type delayed blowback design would have the advantages of eliminating the gas system, saving weight and cost.

In practice it appears that the engineering and materials required to implement delayed blowback makes it pretty much a wash for cost and weight when compared with the M14 or FAL.

BSW

 

[sawdeanz]

In theory it would seem that the HK type delayed blowback design would have the advantages of eliminating the gas system, saving weight and cost.

In practice it appears that the engineering and materials required to implement delayed blowback makes it pretty much a wash for cost and weight when compared with the M14 or FAL.

That's about the conclusion I reached too, good summary.

So that my question doesn't derail this thread completely off topic, I present this:

https://www.youtube.com/watch?v=39tX_7-mkMA&list=UUrfKGpvbEQXcbe68dzXgJuA

The Frommer Stop pistol with a long recoil action. Pretty wacky. There is also such a thing as a blowforward pistol as well. I love the early 1900s in arms manufacture for all the great and not so great innovating they did, but at least they tried.

https://www.youtube.com/watch?v=YKo06FgXlMM&list=UUrfKGpvbEQXcbe68dzXgJuA

 

[Nom de Forum]

Century hack-jobs that are marginal at best

That is being politely understated.

As far as the PSG-1 (don't get me started on how overrated that thing is



Hey it was great in "Sniper" making Billy Zane look like Yuppie scum trying to solve a problem with technology instead of technique.

If you own a Steyr M95, you too will have a special hatred for bolt designs that snap down like that (no clever trick for unlocking the Steyr bolt; you gotta just grab those sharp surfaces and rip the bolt open)

I once owned a Steyr M95. Yaa the bolt on the Steyr is brutally unforgiving, sometimes demanding blood for lubricant before cooperating.


Great videos sawdeanz. That Frommer is the bee’s knees. When everything works right its great, but I imagine trying to clear a feeding or ejection malfunction is nightmare. That Schwarzlose video was cool but if the video had been of a Hino-Komuro being fired it would have been an incredible find. Probably does not exist.

 

[Carl N. Brown]

I think we have drifted far away from the opening question: why the lack of recoil-operated semi rifles? A lot of comments lump recoil, gas and blowback operation with recoil operation.

In all three extraction and ejection is usually aided by residual gas pressure against the cartridge case after the bullet has left the barrel, but they are fundamentally different.

o Recoil operation has a moving barrel. Bolt and barrel are locked together during firing and recoil; the bolt and barrel recoil together and unlock after the bullet has left the barrel and the gas pressure has dropped below levels that would burst the cartridge case.

o Gas operation has a fixed non-moving barrel. Bolt and barrel are locked together before firing; the bolt is unlocked using the force of gas bled off the barrel to allow it to recoil after the bullet has left the barrel.

o Blowback operation has a fixed non-moving barrel. Bolt and barrel are not locked together. Blowback operation relies on the inertia of the bolt to keep the bolt closed until the bullet has left the barrel.

To answer why the lack of recoil-operated semi rifles? I take a sidetrack into why delayed blowback operation was pursued. Back in the early days of semi-auto rifle development John T. Thompson and John Pedersen introduced fixed barrel/hesitation "lock" rifles to avoid the complexity and expense of designs based on recoil or gas operation. Thompson used friction. Pedersen used a jointed bolt. They were not successful. The later Reising used an unlocked tipping bolt with some success as .45 M60 carbine and M50 submachinegun but the .30 carbine version never left the proving ground. Pál Király's Cristóbal design used a lever between a two piece bolt in the .30 Carbine adopted by the Dominican Republic. The StG45/CEAM Modèle 1950/CETME were eventually successful when refined as the HK G3. (However, the Reising, Cristobal and G3 do have their critics.)

What fed interest in the delayed blowback designs for military caliber rifles was the cost and complexity of competing recoil and gas operated designs. In the long run, gas operated rifle designs for high power rifle cartridges and simple blowback operated rifle designs for .22 rimfire and pistol cartridges have proven themselves less expensive and simpler than recoil operated rifle designs. The industry tends to invest in design and production based on what has been proven to work and sell in profitable volume.

The .50 Barrett M82 (M107) semi-auto sniper rifle has been the most successful recoil operated semi-auto rifle design to stay in production and to be widely adopted. But it stands alone as a successful recoil operated semi-auto rifle.

 

[Slamfire]

I am so surprised about the dislike of the HK roller bolt rifles as I think they are an excellent military rifle. Most of the dislikes center around preferences, primarily preferences about ergonomics. As a consumer you are perfectly entitled to decide about your preferences, it is all about how you make your system trades, decide what is important to you. I remember taking a System Engineering class and the class example was a system trade on a vehicle, each group had to pick five characteristics and rank them. It was interesting to see what each group decided was the most important, the girl group, their most important preferences were all about safety, the EEO group, among their top five was “radio”, my group ignored safety, my group rated performance highest, did not care if we died in a flaming wreck, as long as we got there fast, but generally cost, reliability, comfort were in the top five of every group. However, when it came to creating priorities for employee vehicles the absolute top priority was cost and comfort was not in the top five.

The decision makers who are procuring hundred’s of millions of dollars worth of service rifles have a different priority set than an individual buying a personnel weapon. Barnbwt just assumes that whatever weapon he buys is reliable, safe, easy to maintain, but these characteristics are not necessarily so, they have to prioritized and accounted for, and built into the weapon.

I am of the opinion that the German designers of the CETME took a long hard look at their WW2 experience and prioritized cost and easy fabrication above all. You can currently buy a new PTR 91 for $1000, and the price goes up. I am surprised to see the cheapest DSA FAL is $975, the next level up is $1,700, but when the last new FN made FALs were sold in the US, they cost (adjusted for inflation) $3,000. The M14 was a very expensive rifle to build, M1a’s are not cheap, prices are not on the Springfield Armory web site, but the last I looked, a rack grade M1a was $1500-$1700. A forged receiver Rockola M14F, new, is $2,170. http://www.atlanticfirearms.com/com...ola-m14-308-battle-rifle-detail.html?Itemid=0

Even a dollar additional cost adds up quickly for a million rifle procurement. Complaints about ergonomics are not going to be taken seriously by a group whose job is to purchase the lowest cost service rifle that meets the minimum requirements. These decision makers also have to make the trade, is it better to have all the costly niceties and slow production rate down? There will be unlucky guys who don’t get a rifle and have to carry broom sticks. Think that bothers them? Anyone watch the movie “Enemy at the Gates”? One guy gets a rifle and the next gets a five round clip and is told to pick up a rifle from a dead companion. For all I know, that might have been true, the Russians had a heck of a time making enough equipment at various stages of the war. So did the Germans who lost Armies in Russia. Just look at the stripped down bare essentials of the Japanese and German last ditch weapons. Sure, everyone wants all the neat, costly features of an expensive weapon, but when decision makers look at National Survival and balance that against gripes about selector switch location, their top five list of desirable weapon characteristics look a lot different.

From what I understand, the HK roller bolts are the least expensive to make of any of the 308 issue service rifles, which is probably why they are still standard issue front line issue when all the other contemporary rifles, FN, M14, are not.

In theory it would seem that the HK type delayed blowback design would have the advantages of eliminating the gas system, saving weight and cost.

Ludwig Vorgrimler and his design crew certainly would have looked at gas operation but their design eliminated a number of parts, and did not require a milled receiver. Looking at my PTR91, I would say the bolt and barrel are the most difficult to make parts of the rifle, the receiver is stamped, welded sheet metal. It takes a lot less time to train someone to weld a bead than it does to train a machinist. To me, the Germans did not consider rebuild in the CETME design. Refurbishment and rebuild actually take effort from making a new rifle. I am certain they figured out they could rebuild ten rifles but with the same effort make 20 new. Compliants about requiring a manufacturing facility should not be taken seriously, just what back woods blacksmith is going to make a tank on his anvil?

In practice it appears that the engineering and materials required to implement delayed blowback makes it pretty much a wash for cost and weight when compared with the M14 or FAL.

Depends on the delayed blowback design, but when comparing the roller bolts with the M14 or FAL, the cost advantage is with the roller bolts. The less parts, the less parts you have to make, account for, spare for, have in inventory. The less parts, the better logistically. I don’t know why HK eventually dropped the roller bolt and went to a gas system for their 223 rifles.

I for one sure as heck would not want to hump a 14 pound rifle all day long. Weapon weight is not a consideration for those who drive every where, but if you are ever so unlucky to get drafted in a major war, you will find that only a few Officers get to sit on their butts and watch the country side go by. The Ground Pounder gets to carry about 100 pounds of gear and hates dragging heavy weapons around.


I got to shoot a Frommer Stop pistol, nasty sharp recoil for such a small cartridge. Also, pistol disassembly was complicated and not obvious.

 

[Nom de Forum]

I am so surprised about the dislike of the HK roller bolt rifles as I think they are an excellent military rifle. Most of the dislikes center around preferences, primarily preferences about ergonomics.....

The ergonomics you dismiss so lightly can be life saving. Having your rifle inform you it is out of ammunition and it is time to reload is important and designing it to do is so easy and cheap it is ridiculous to cut that cost. Having a rifle with a safety the hinders disengagement is a real problem in reacting to an ambush. Having a rifle that is heavy and awkward to use reduces the ability of the users to gain fire superiority and is a foolish way to reduce costs.

These decision makers also have to make the trade, is it better to have all the costly niceties and slow production rate down? There will be unlucky guys who don’t get a rifle and have to carry broom sticks.

The Germans were never going to run out of rifles in the 1960s as long as the United States had millions of M1 Garands in storage.

From what I understand, the HK roller bolts are the least expensive to make of any of the 308 issue service rifles, which is probably why they are still standard issue front line issue when all the other contemporary rifles, FN, M14, are not.

Standard issue in Armys that can’t or will not pay the expense of something much better for numerous reasons.

Ludwig Vorgrimler and his design crew certainly would have looked at gas operation but their design eliminated a number of parts, and did not require a milled receiver. Looking at my PTR91, I would say the bolt and barrel are the most difficult to make parts of the rifle, the receiver is stamped, welded sheet metal. It takes a lot less time to train someone to weld a bead than it does to train a machinist. To me, the Germans did not consider rebuild in the CETME design. Refurbishment and rebuild actually take effort from making a new rifle. I am certain they figured out they could rebuild ten rifles but with the same effort make 20 new. Compliants about requiring a manufacturing facility should not be taken seriously, just what back woods blacksmith is going to make a tank on his anvil?

I think the some of the story is an example of engineering philosophy being to impress other engineers with clever and unique engineering with little thought about efficient operation by the individual user, and an unhealthy dose of NIH syndrome influencing decisions. They could probably make something like a 7.62 Nato AKM clone just as cheap. Don’t dismiss back woods blacksmithing until you examine some of the copies of rifles made in Afghanistan and Pakistan, although I don't think the complexities of making a roller delayed blowback action have been successful.

I don’t know why HK eventually dropped the roller bolt and went to a gas system.....

Because almost nobody says they want it. The most extreme example of dislike I have read is from “Testing the War Weapons”. The author, Timothy J. Mullin, after making a long list of complaints about the user unfriendliness states “Given a choice between a G3 and an M1917 Enfield .30-06, I would take the Enfield”. I wouldn’t take the Enfield but I would take just about any other modern military rifle instead.

I got to shoot a Frommer Stop pistol, nasty sharp recoil for such a small cartridge. Also, pistol disassembly was complicated and not obvious.

I envy you for the experience.

 

[briansmithwins]

Looking at my PTR91, I would say the bolt and barrel are the most difficult to make parts of the rifle, the receiver is stamped, welded sheet metal.

Forget the barrel, that's just a steel tube that has rifling impressed on the inside by running it through a CHF machine.

Now the bolt, trunnion, and locking piece, those are going hard to make. You need steel that's hardenable to ~56-58 RC and that's tough enough to take firing shock w/o cracking. Guys that have made new locking pieces have used high alloy steel and then surface ground the ramps the roller interface with to maintain tolerance.

Using a separate locking piece from the bolt carrier was smart, though. It let the part that needed to be massive be made from cheap carbon steel, with the locking piece effectively being a replaceable insert.

BSW

 

[barnbwt]

"Barnbwt just assumes that whatever weapon he buys is reliable, safe, easy to maintain"

I built that STGW57 myself. I take nothing for granted, and got nothing easily in that build. It was still an easier build than a G3, though . The G3 scales nicely in terms of mass production, but is not so easy for a small shop. Fancy dies and machined forgings require a good deal of tooling and industrial scale.

Which is why I wonder why Barrett-like rifles in "infantry" calibers* are not more common, military or sporting. Like the AR, the barrel and extension are the only parts requiring tooling, and they are easily sourced commodities, now. Everything else is largely non-structural, and only needs to hold a few critical tolerances (also like the AR, which can be made quite sloppily and still function, so long as drop in modularity isn't a priority). I think production could be as easy as an AK for the builder, but without the need for expensive/imported machined trunnions. The advantage is probably just that a small shop may be able to make it cheaper, and that it probably will run more cleanly than any gas op system (that's admittedly not a very compelling benefit ). Plus you get a 223 that actually gives some tactile feedback to let you know it fired

TCB

*Apparently my 223 rifle concept is uncannily similar to the Barrett M82 action. I may solicit MachIVShooter to make a 1/2 scale replica to go with his AR in 17WMR...

 

[barnbwt]

"Forget the barrel, that's just a steel tube that has rifling impressed on the inside by running it through a CHF machine"
On any other barrel, yes. But we need those blasted flutes, so it's either hammer forging or EDM (or a fluted reamer ). Only a few shops can accomodate chamber flutes (like the US made backup barrel in 308 for the STGW). When you actually go to build one from non-OEM parts, you'll find yourself reaching for any design solution that avoids sourcing a fluted chamber reamer

TCB

 

[Slamfire]

I am so surprised about the dislike of the HK roller bolt rifles as I think they are an excellent military rifle. Most of the dislikes center around preferences, primarily preferences about ergonomics.....

The ergonomics you dismiss so lightly can be life saving. Having your rifle inform you it is out of ammunition and it is time to reload is important and designing it to do is so easy and cheap it is ridiculous to cut that cost.

I got to talk to a combat veteran of Iraq and Afghanistan about this issue. I asked him whether in the excitement of combat he could tell whether his rifle was empty, whether he could tell whether the bolt was locked back, which all lead to the issue of a quick magazine change. Speed was not something he was concerned about. I still remember the eyes of this Gent, looking at me, and his comment: “Don’t you realize that I have 16 other Soldiers with me?” Well, no I did not. I don’t have a CIB, my combat tactics come from movies, video games, and combat courses. The hero in the movie only has one hour and a half to kill all the evil guys till the movie ends and of course, he kills a lot of evil guys, quick magazine changes and all, till his shirt tears off showing his fine muscular torso after which then, he is obligated to kung fu his way to the end of the movie. But, it is all about him. One hero actor against legions of bad guys. We have all played video games and there a slow reload will get you killed, which is a bother, because you have to go back to the spawning point . Wonderful thing about video games, you get to come back, and of course, it is you, only you, against legions of bad guys. The self defense courses, these are timed events. The shooter who clears the room fastest, by himself, of course, wins.

I am beginning to think, in real life, that these tactics might actually be suicidal. Trying to clear a room, building, by yourself, with your favorite thunderstick, and to do it as fast as possible, is probably a good way to get yourself killed. I can think of a number of better options. Pull back, let the heavy machinegun perforate the place, keeping the bad guys down, while someone shoots an AT4 through the front door. Or, call in artillery, or ask the friendly skies to drop some napalm and enjoy the barbeque. Who said real battles have to be over in an hour and half?. Racing against a clock can get you dead, and in the real world, when you are dead, you don’t come back to a spawn point.

I do like my bolt hold open in my Garands, M1a’s, and AR15’s. It allows me to shoot single shot, prone with a sling, during highpower matches. But I am beginning to think, that is why it is there. The US military used to shoot KD bullseye and every rifle since the Trapdoor has features best suited to the target shooting game. The Army used to think bull’s-eye represented combat training, but that sort of went away in the 60’s. I did take my PTR91 to a local reduced course, 100 yard, across the course (XTC) match and found that it is was totally unsuited to the game. I had to load my rapid fire magazines, 3 rounds and 7 rounds. You are required to make a RF reload. Cocking the PTR requires a huge shift of position, so for sitting RF and prone RF, I fired two rounds, put the safety on, inserted the seven round magazine, and fired till the gun was empty. It was impossible to shoot 20 rounds prone slow gun empty, single shot, without breaking position, so I got permission from the match director to shoot 20 rounds from a loaded magazine. The PTR91 design is definitely not the rifle to shoot in an XTC match. But XTC is a game, and I have had fellow shooters who were combat veterans, tell me that.

But back to that bolt hold open device, my WASR does not have one. I don’t have any others, nor have I handled all the variants of the AK 47, but I suspect none of the rifles has a bolt open device and the Kalashnikov seems to be a very popular battle rifle all things considered. So maybe, a bolt hold open device is just a nice to have, not all that important outside of movies, video games, and combat course games.

These decision makers also have to make the trade, is it better to have all the costly niceties and slow production rate down? There will be unlucky guys who don’t get a rifle and have to carry broom sticks.

The Germans were never going to run out of rifles in the 1960s as long as the United States had millions of M1 Garands in storage.

Well for a time we had a rifle shortage in the early 60’s. The DCM sold a number of M1’s that were rebuilt in the early 60’s, these rifles have a penciled location and date (like RRAD 6-63) on the receiver tang. The Army did not have enough M14’s around and was rebuilding M1 Garands just in case the balloon went up. I have a bud, who was in the 82 Airborne during the Cuban missile crisis. He was in active status (which meant within 24 hours they were ready to drop anywhere) and when given the notice to ready up , he traded his M1 carbine for a M1 Garand because, as he said, the “M1 carbine was a nice gun to play solider”, but he did not want to drop on Cuba with one. His unit, in 1962, did not have M14’s, but was going to be one of the very first to be dropped in a war. His almost claim to fame was that it was going to be a race between him, and the guy on the other side of the plane, as to who would hit Cuba first. Later he found, the drop point was a killing zone for all things American. Still, I was very surprised that the first responders did not have M14’s. Given the lack of M14’s, I don’t know how many M1 Garands the US would have given up to an ally.

If you read this months "Military History" and the article about what would have happened if Russia invaded the West, anything not already in Germany, would have arrived after the Russians captured the county.

They could probably make something like a 7.62 Nato AKM clone just as cheap.

Don’t know, but the AK and its round was a very pragmatically designed weapon, and a very good one. Not adopting the AK was truly an example of not invented here.

 

[briansmithwins]

Not adopting the AK, FAL, British 6.5mm class assault rifle round, adopting the M60 and M14 and the shenanigans related to the AR15 are all very good examples of Army Ordinance's mentality about what was developed by them and therefore perfect.

When the Swiss we're looking for a replacement for the StG57 rifles they picked the AK and pretty much copied it straight across, except for the trigger mechanism.

As far as bolt hold opens go, if the Soviets (AK47), German Army (G3), and Brits (L1A1) had wanted a BHO they would have designed one in. The Brits had to delete the automatic BHO
on the L1A1 because they didn't want it. BHOs are not without demerits, they allow more garbage into the gun and are yet one more control that needs to be trained on.

BSW

 

[Nom de Forum]

I got to talk to a combat veteran of Iraq and Afghanistan about this issue. I asked him whether in the excitement of combat he could tell whether his rifle was empty, whether he could tell whether the bolt was locked back, which all lead to the issue of a quick magazine change. Speed was not something he was concerned about. I still remember the eyes of this Gent, looking at me, and his comment: “Don’t you realize that I have 16 other Soldiers with me?” Well, no I did not. I don’t have a CIB, my combat tactics come from movies, video games, and combat courses. The hero in the movie only has one hour and a half to kill all the evil guys till the movie ends and of course, he kills a lot of evil guys, quick magazine changes and all, till his shirt tears off showing his fine muscular torso after which then, he is obligated to kung fu his way to the end of the movie. But, it is all about him. One hero actor against legions of bad guys. We have all played video games and there a slow reload will get you killed, which is a bother, because you have to go back to the spawning point . Wonderful thing about video games, you get to come back, and of course, it is you, only you, against legions of bad guys. The self defense courses, these are timed events. The shooter who clears the room fastest, by himself, of course, wins.

I am beginning to think, in real life, that these tactics might actually be suicidal. Trying to clear a room, building, by yourself, with your favorite thunderstick, and to do it as fast as possible, is probably a good way to get yourself killed. I can think of a number of better options. Pull back, let the heavy machinegun perforate the place, keeping the bad guys down, while someone shoots an AT4 through the front door. Or, call in artillery, or ask the friendly skies to drop some napalm and enjoy the barbeque. Who said real battles have to be over in an hour and half?. Racing against a clock can get you dead, and in the real world, when you are dead, you don’t come back to a spawn point.

I do like my bolt hold open in my Garands, M1a’s, and AR15’s. It allows me to shoot single shot, prone with a sling, during highpower matches. But I am beginning to think, that is why it is there. The US military used to shoot KD bullseye and every rifle since the Trapdoor has features best suited to the target shooting game. The Army used to think bull’s-eye represented combat training, but that sort of went away in the 60’s. I did take my PTR91 to a local reduced course, 100 yard, across the course (XTC) match and found that it is was totally unsuited to the game. I had to load my rapid fire magazines, 3 rounds and 7 rounds. You are required to make a RF reload. Cocking the PTR requires a huge shift of position, so for sitting RF and prone RF, I fired two rounds, put the safety on, inserted the seven round magazine, and fired till the gun was empty. It was impossible to shoot 20 rounds prone slow gun empty, single shot, without breaking position, so I got permission from the match director to shoot 20 rounds from a loaded magazine. The PTR91 design is definitely not the rifle to shoot in an XTC match. But XTC is a game, and I have had fellow shooters who were combat veterans, tell me that.

But back to that bolt hold open device, my WASR does not have one. I don’t have any others, nor have I handled all the variants of the AK 47, but I suspect none of the rifles has a bolt open device and the Kalashnikov seems to be a very popular battle rifle all things considered. So maybe, a bolt hold open device is just a nice to have, not all that important outside of movies, video games, and combat course games.

Feel better after getting that all off your chest? Good grief no one is claiming a bolt hold open device is necessary because of the need to be making routine “Gun Game” type rapid reloads in combat. Your combat veteran friend’s opinion is realistic in that combat is played as a team sport by those who want to live. However for him to say he was not concerned with speed in getting his empty rifle back to firing makes me wonder about the variety of his combat experiences. I don’t play video games, war movies frequently make me laugh at what they portray, I haven’t played the gun games in decades because I realized they teach to many bad/suicidal habits, and the only worthwhile combat courses I attended were courtesy of the U.S. Army. I was taught to reload a rifle as a quickly as possible so I could support those “16 other soldiers with me” to keep them and me alive. The bolt hold open feature makes that easier and even if the soldier does not immediately notice the feeling his bolt has locked back he will get the rifle back in action faster releasing it than he would having to pull back a charging handle from its forward position. This last point is especial true when compared to the gawd awful heavy and long pull of a H&K G3. By the way have you considered that a wounded soldier incapable of charging a G3 for reloading may very well be able to do so with a M16, M14, and even a FAL. Of all those rifles none of them is more in need of a bolt hold open feature than a G3. Lack of a bolt hold open device as a standard feature on the Kalashnikov has been a concern of some users and there have been attempts to correct that flaw. One of those attempts is nothing more expensive than changing out the magazine follower to one that will hold the bolt open on the last shot.

Well for a time we had a rifle shortage in the early 60’s. The DCM sold a number of M1’s that were rebuilt in the early 60’s, these rifles have a penciled location and date (like RRAD 6-63) on the receiver tang. The Army did not have enough M14’s around and was rebuilding M1 Garands just in case the balloon went up. I have a bud, who was in the 82 Airborne during the Cuban missile crisis. He was in active status (which meant within 24 hours they were ready to drop anywhere) and when given the notice to ready up , he traded his M1 carbine for a M1 Garand because, as he said, the “M1 carbine was a nice gun to play solider”, but he did not want to drop on Cuba with one. His unit, in 1962, did not have M14’s, but was going to be one of the very first to be dropped in a war. His almost claim to fame was that it was going to be a race between him, and the guy on the other side of the plane, as to who would hit Cuba first. Later he found, the drop point was a killing zone for all things American. Still, I was very surprised that the first responders did not have M14’s. Given the lack of M14’s, I don’t know how many M1 Garands the US would have given up to an ally.

That is all very interesting but irrelevant. The Bundeswehr was not lacking in arms before the adoption of the G3. The soldats were already armed with M1 Garands, G1s a.k.a. FN-FALs, and even played around with a few G2s a.k.a SIG 510s before going with the cheaper G3. I doubt the war would have lasted long enough to expend all of those but if it did the U.S. would have had time to resupply the Herms.

If you read this months "Military History" and the article about what would have happened if Russia invaded the West, anything not already in Germany, would have arrived after the Russians captured the county.

I was stationed in Germany during the 1980s and 1990. I was one of the few soldiers who did not believe the story that the war would start after a period of rising tensions followed by obviously noticed pre-combat deployments. After the fall of The Wall, I was in Berlin during the fall, documents from the East showed that the Soviet Bloc was prepared to make a significant attack on almost a moments notice with little indication that would warn the West. I was right in my belief that if my unit just happened to be already deployed the duration of my wartime mission would probably be measured in minutes before I was killed or running for my life after all our equipment was destroyed by artillery and being overrun.

 

[Nom de Forum]

Not adopting the AK, FAL, British 6.5mm class assault rifle round, adopting the M60 and M14 and the shenanigans related to the AR15 are all very good examples of Army Ordinance's mentality about what was developed by them and therefore perfect.

When the Swiss we're looking for a replacement for the StG57 rifles they picked the AK and pretty much copied it straight across, except for the trigger mechanism.

As far as bolt hold opens go, if the Soviets (AK47), German Army (G3), and Brits (L1A1) had wanted a BHO they would have designed one in. The Brits had to delete the automatic BHO
on the L1A1 because they didn't want it. BHOs are not without demerits, they allow more garbage into the gun and are yet one more control that needs to be trained on.

BSW

Apparently the Brits recognized their error in not having a BHO when they replaced the L1A1.

 

[briansmithwins]

I don't think the replacement (SA80) can be held up as a example of good design.

BSW

 

[Nom de Forum]

I don't think the replacement (SA80) can be held up as a example of good design.

BSW

Ironically it was H&K that cleaned-up the design faults to make it a good rifle.

Something else of note about BHO devices on rifles. The Israelis have one on their Tavor. Few countries have more experience using rifles in combat than the Israelis. I doubt the U.S.A. will omit the BHO on whatever rifle eventually replaces the M16 series, since the U.S. Army also has quite a bit of experience using rifles in combat. Are any new combat rifle designs, other than Russian, omitting BHO? I think the real reason some of the rifle designs since the 1940s omitted BHO was because the designs could not have an attached detachable box magazine reloaded with stripper clips and the designers never took sufficient time to consider other advantages of having a BHO feature. Some of the T48s ended up being used at the 18B school. I always thought a FAL you could reload with stripper clips was I great idea.